Achromobacter denitrificans: The type species of gram negative, aerobic bacteria in the genus ACHROMOBACTER. Previously in the genus ALCALIGENES, the classification and nomenclature of this species has been frequently emended. The two subspecies, Achromobacter xylosoxidans subsp. denitrificans and Achromobacter xylosoxidans subsp. xylosoxidans are associated with infections.Achromobacter: A genus of gram-negative, strictly aerobic, non-spore forming rods. Soil and water are regarded as the natural habitat. They are sometimes isolated from a hospital environment and humans.Alcaligenes faecalis: The type species of gram negative bacteria in the genus ALCALIGENES, found in soil. It is non-pathogenic, non-pigmented, and used for the production of amino acids.Paracoccus denitrificans: A species of bacteria isolated from soil.Alcaligenes: A genus of gram-negative, aerobic, motile bacteria that occur in water and soil. Some are common inhabitants of the intestinal tract of vertebrates. These bacteria occasionally cause opportunistic infections in humans.Gram-Negative Bacterial Infections: Infections caused by bacteria that show up as pink (negative) when treated by the gram-staining method.